FAIR VALUE OF FINANCIAL INSTRUMENTS - Carrying Value (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Credit Facility
Fair Value Of Instruments [Line Items]
Carrying value of debt	$ 260,500	$ 262,000
Fair value of debt	260,826	261,345
Senior Notes
Fair Value Of Instruments [Line Items]
Carrying value of debt	218,094	217,929
Fair value of debt	234,451	237,134
Finance Method Lease Obligations
Fair Value Of Instruments [Line Items]
Carrying value of debt	0	0
Letter of credit
Fair Value Of Instruments [Line Items]
Carrying value of debt	$ 670	$ 620

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

Name:	us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant